Paspalum dilatatum Poiret, dallis grass. Perennial herb, rhizomatous, fibrous–rooted, several–stemmed at base, cespitose, unbranched from base, with ascending to spreading inflorescences, in range to 80+ cm tall; shoots pilose at plant base (sheaths), essentially glabrous above; rhizomes short—40+ × 4—10 mm, white aging yellowish, internodes conspicuously strigose just below node; adventitious roots nodal on rhizome.
Stems (culms) compressed in internodes, to 5 mm diameter, tough, nodes often bent (geniculate) at nodes and brownish, glabrous; internodes pithy to hollow for short intervals.
Leaves alternate distichous, simple with sheath; prophyll ovate, to 20 mm long, 2–keeled with strongly infolded margins, glabrous; sheath of foliage leaves open, to 180 mm long, somewhat keeled and with slightly raised veins, conspicuously pilose (basal leaves) to glabrous or pilose on margins above node (most cauline leaves), without lobes (auricles) at top; ligule membranous, obtuse, 2—5.5 mm long, translucent–gray becoming brownish; collar pale green, pilose on upper side; blade linear, 45—570 × 4—12 mm, the widest at or above midblade, flat, minutely toothed on margins from base to tip, long–tapered to tip, parallel–veined with veins raised on both surfaces, midrib slightly sunken and whitish on upper surface and raised on lower surface, upper surface pilose at base at collar.
Inflorescence spikelets, in terminal panicles with 3—7(—11) spikelike branches, panicle with spreading, lax branches, branches 1 per node, 1–sided having 2 rows of overlapping spikelets on lower side, 30—115 × 3 mm, first branch the longest decreasing upward, spikelets in alternating pairs along central ridge, spikelet with 2 florets with lower one sterile and upper one fertile, bracteate, lacking awns; peduncle somewhat compressed, 120—500+ mm long, tough; bract subtending branch absent; principal panicle axis channeled and hemi–cylindric, ± 0.6 mm diameter, glabrous; branch base long–pilose and sometimes minutely puberulent, rachis ribbonlike, ± 1.3 mm wide, upper surface (lacking spikelets) with white midvein, lower surface with paired stalks of spikelets arising alternately along central ridge and lateral wings sometimes wavy; stalks of paired spikelets fused at point of attachment to rachis, flattened on upper side.
Spikelet compressed–ovate, breaking below glume; glume 1, lower glume absent, upper glume ovate, 3.5—3.7 × 2.2—2.4 mm, greenish white, with 5 or 7 veins converging at tip, with long silky hairs; lemma (lower floret) ca. 0.2 mm < upper glume, flat, (3—)5—6–veined, with long silky hairs at inrolled margins, lemma (upper floret) ca. 2.2 × 1.7 mm, stiff (chartaceous), veins obscure, with inrolled margins, glossy, glabrous; palea (upper floret) enclosed by margins of lemma, glabrous, the exposed surface flat, chartaceous, the incurved margins membranous while extending to midpoint and enveloping flower, open at top.
Flower bisexual; perianth (lodicules) 2, very fleshy, inversely conic to inversely pyramidal and 3–lobed at anthesis, ca. 0.3—0.5 mm long, white; stamens 3, free; filaments threadlike, ± 3 mm long, white; anthers exserted, dorsifixed, dithecal, linear, 1—1.3 mm long, burgundy or purplish pink, longitudinally dehiscent; pollen yellowish white; pistil 1; ovary superior, compressed–obovoid to compressed–fusiform with blunt ends, ± 0.7 mm long, translucent, glabrous, 1–chambered with 1 ovule; styles 2, translucent, ca. 1 mm long; stigmas exserted from lemma near midpoint, bottlebrushlike, ± 2 mm long, purple to burgundy.
Fruit achene (caryopsis), enclosed by infolded palea, unit flattened and ± round, 1.9—2.1 mm long, straw–colored to yellowish, concave on 1 side and convex on other side; achene permanently retained, thinly lens–shaped and broadly ovate, slightly smaller than palea.
A. C. Gibson & B. A. Prigge